In recent years the use of hard, dense ceramic materials on surfaces subjected to the abrasive action of screen conveyors or other moving metallic elements has become rather widespread. U.S. Pat. No. 3,067,816, for instance, describes the utilization of self-bonded and metal-bonded ceramics on suction-box covers underlying the upper run of a screen conveyor carrying a slurry of wood pulp and water in a Fourdrinier paper-making machine. Later developments, e.g. as described in Austrian Pat. Nos. 279,334, 280,034 280,035, 280,036 and 313,697, involve the use of sintered ceramics for such purposes.
Such supports, which in paper-making equipment have to extend across the full width of the transport path for the slurry, generally have lengths of several meters. Depending on their use as drainage elements or as simple supporting strips, they may or may not be slotted or otherwise perforated. In any case it is necessary, for practical reasons, to manufacture them in a multiplicity or relatively short sections adjoining one another along generally transverse lines which, as shown in the above-identified U.S. patent, may include an acute angle with the transport direction.
Unavoidable manufacturing tolerances and warping of these relatively thin plate sections prevent their accurate alignment without intervening gaps in a mounting frame unless each section is carefully machined to its specified dimensions prior to assembly; such machining, of course, greatly increases the production costs. Furthermore, the clamping stresses exerted by the mounting frame may cause some of the section edges to rise up from the plate surface, thereby damaging the screen passing thereover.